Make chrome/ be documentElement/body agnostic with regards to scrollTop/Left

chrome/browser/resources/about_memory.js

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 function reload() {
   if (document.getElementById('helpTooltip'))
     return;
   history.go(0);
 }
 
@@ skipping 24 matching lines @@
   el.id = 'helpTooltip';
   el.innerHTML = event.toElement.getElementsByTagName('div')[0].innerHTML;
   el.style.top = 0;
   el.style.left = 0;
   el.style.visibility = 'hidden';
   document.body.appendChild(el);
 
   var width = el.offsetWidth;
   var height = el.offsetHeight;
 
-  if (event.pageX - width - 50 + document.documentElement.scrollLeft >= 0)
+  var scrollLeft = scrollLeftForDocument(document);
+  if (event.pageX - width - 50 + scrollLeft >= 0)
     el.style.left = (event.pageX - width - 20) + 'px';
   else
     el.style.left = (event.pageX + 20) + 'px';
 
-  if (event.pageY - height - 50 + document.documentElement.scrollTop >= 0)
+  var scrollTop = scrollTopForDocument(document);
+  if (event.pageY - height - 50 + scrollTop >= 0)
     el.style.top = (event.pageY - height - 20) + 'px';
   else
     el.style.top = (event.pageY + 20) + 'px';
 
   el.style.visibility = 'visible';
 }
 
 function handleHelpTooltipMouseOut(event) {
   var el = document.getElementById('helpTooltip');
   el.parentNode.removeChild(el);
@@ skipping 10 matching lines @@
 
 document.addEventListener('DOMContentLoaded', function() {
   // This is the javascript code that processes the template:
   var input = new JsEvalContext(loadTimeData.getValue('jstemplateData'));
   var output = document.getElementById('t');
   jstProcess(input, output);
 
   enableHelpTooltips();
 });